Unknown binding types are ignored at run time

Steps:
- Create a default C# http function
- Add this binding:

```
{
"type": "bogus",
"name": "blah",
"direction": "out"
}
```

I expected it to complain, but it just ignored it.

This is making it hard to debug issues with BYOB scenarios, because it's not clear whether it knows about the binding.

Reproduce this with a default C# HTTP function and the shown unknown binding in its configuration. Trace how the host parses and handles binding types, then verify that an unsupported type produces a clear diagnostic rather than being ignored; the payload names no source file or regression test.

Written by the indexing model from the issue text.